CA1205939A

CA1205939A - Thermoplastic composition

Info

Publication number: CA1205939A
Application number: CA000411017A
Authority: CA
Inventors: Akitoshi Ito; Hajime Sakano; Yasuo Takabori; Yoshitugu Fujimori
Original assignee: Honda Motor Co Ltd; Sumika Polycarbonate Ltd
Current assignee: Honda Motor Co Ltd; Sumika Polycarbonate Ltd
Priority date: 1981-09-09
Filing date: 1982-09-08
Publication date: 1986-06-10
Also published as: AU553028B2; AU8812482A; EP0074112B2; EP0074112B1; EP0074112A1; DE3277772D1; US4438229A

Abstract

ABSTRACT
THERMOPLASTIC COMPOSITION
A thermoplastic composition which comprises a blend comprising 20 to 80 % by weight of a polycarbonate resin and 80 to 20 % by weight of a graft polymer obtained by grafting at least one aromatic vinyl compound and at least one of vinyl cyanides and alkyl unsaturated carboxy-lates onto a conjugated diene rubber or its mixture with a copolymer of at least one aromatic vinyl compound and at least one of vinyl cyanides and alky unsaturated carboxy-lates in an amount of not more than 90 % by weight on the basis of the combined amount of the graft polymer and the copolymer, and a polyolefin or a plasticizer having a light transmission of not less than 70 % when determined on the film of 20 microns in thickness prepared by the use of a solution of the plasticizer (0.25 g) and acrylonitrile-styrene copolymer (weight ratio of acrylonitrile and styrene, 30 : 70; 0.75 g) in acetone (10 ml), the weight proportion of the blend and the polyolefin or the plasti-cizer being 100 : 0.2 - 20. The resulting composition is excellent in solvent resistance, welding strength, impact resistance, molding property, etc.

Description

2~9~g The present invention relates to a thermoplastic composition. More particularly, it relates to a thermo-plastic resin composition excellent in solvent resistance, weld strength, impact resistance, molding property, etc.
Hitherto, attempts have been made to improve the molding property and the dependency of the impact strength on thickness of polycarbonate resins by incorporating therein diene rubber graft polymers such as ABS resins (acrylonitrile-butadiene-styrene polymers) or M~S resins (methyl methacrylate-butadiene-styrene polymers~ (cf.
Japanese Patent Publns. (examined) Nos. 15225/1963, 71/196 and 11496/19673. Attempts have also been made to improve the impact strength of polycarbonate resins by incorporating therein ABS resins manufactured by bulk-suspension poly-meri~ation (cf. Japanese Patent Publn. (examined~ No.
11142/1976). However, the resulting compositions are only improved in apparent molding property, and when a plurality of gates are provided in in~ection molding as the most popular molding procedure, the strength at the welded parts is insufficient. Also, the resistance to solvent is un-satisfactory.
As a result of the extensive study for providing a thermoplastic composition comprisin~ a polycarbonate resin and a graft polymer as the essential components and improved in chemical and physical properties, particularly in solvent resistance and weld strength, it has now been found that - 2 ~ ~

incorporation of a small amount of a polyolefin or a certain plasticizer into such composition is effective in improve-ment of solvent resistance and weld strength. Advantage-ously~ the resulting composition is excellen-t in process-ability.
The thermoplastic composition o~ the invention comprises a blend comprisin~ 20 to 80 % by weight of a polycarbonate resin and 80 to 20 % by weight of a graft polymer obtained by grafting at least one aromatic vinyl compound and at least one of vinyl cyanides and alkyl un-saturated carboxylates onto a conjugated diene rubber or its mixture with a copolymer of at least one aromatic vinyl compound and at least one of vinyl cyanides and alky un-saturated carboxylates in an amount of not more than 90 %
by weight on the basis of the combined amount of the graft polymer and the copolymer, and a polyolefin or a plasticizer having a light transmission of no~ less than 70 % when determined on the film of 20 microns in thickness prepared by the use of a solution of the plasticizer (0.25 g) and acrylonitrile-styrene copolymer (weight ratio of acrylo-nitrile and styrena, 30 : 70; 0.7S g) in acetone (10 ml), the weight proportion of the blend and the polyolefin or the plasticizer being 100 : 0.2 - 20.
As the polycarbonate resin, there may be used any one chosen from aromatic polycarbonates, aliphatic poly-carbonates, aliphatic aromatic polycarbonates, etc. Examples are polymers comprising units of bisphenol such as 2,2 bis(4-hydroxyphenyl)alkanes, bis(4~hydroxyphenyl)ethers, 93~
~ - 3 -bis(4-hydroxyphenyl)sulfones, bis(4-hydroxyphenyl~sulfides and bis(4-hydroxyphenyl)sulfoxides. When desired, said bisphenols may be substituted with halogen. These and other polycarbonate resins and -their production are explained in detail in Encyclopedia of Polymer Science and Technology, 10, p. 710-764 (1969) (published by John Wiley and Sons, Inc.) and literatures cited therein.
As the graft polymer, there is used the one grafting at least one aromatic vinyl compound and at least one of vinyl cyanides and alkyl unsatura~ed carboxylates onto a conjugated diene rubber. Examples of the conjugated diene rubber are polybutadiene, butadiene--styrene copolymer, butadiene-acryloni~rile copolymer, etc. Examples of the aromatic vinyl compouna are styrene, a-methylstyrene, dimethylstyrene, vinyltoluene, etc. ~xamples of the vinyl cyanide are acrylonitril~, methacrylonitrile, etc. Examples of the alkyl unsatur`ated carboxylate are lower alkyl acrylates ~e.g. methyl acrylate, ethyl acrylate, butyl acrylate), lower alkyl methacrylates ~e.g. methyl methacrylate, ethyl meth-acrylate, butyl methacrylate), hydroxy~lower)alkyl acrylate te.g. hydroxyethyl acrylate), hydroxy(lower)alkyl meth-acrylate (e.g. hydroxyethyl methacrylate, hydroxypropyl methacrylate), etc. The weight proportion of the conjugated diene rubber and the monomeric components in the graft polymer may be usually from 5 : 95 to 70 : 30. Further~ the weight proportion of the aromatic vinyl compound and the other monomeric component(s) consisting of the vinyl cyanide and/or the alkyl unsaturated carboxylate may b~ normally ~L2~

from S0 : 50 to 80 : 20.
As the copolymer, there may be used any copolymer of at least one aromatic vinyl compound with at least one of vinyl cyanides and alkyl unsaturated carboxylates. Examples of the aromatic vinyl compound, the vinyl cyanide and the alkyl unsaturated carboxylate are those as stated above.
The weight proportion of the aromatic vinyl compound and the other monomeric component(s) consisting of the vinyl cyanide and/or the alkyl unsaturated carboxylate may be usually from 55 : 45 to 85 : 15, although this is not essential. Further, the intrinsic viscosity of the copolymer is preferred to be from 0.60 to 1.50 (determined in dimethylformamide at 30C), but this is not limitative.
The contents of the polycarbonate resin and the graft polymer or its mixture with the copolymer may be ordinarily from 20 to ~0 % by weight (preferably from 30 to 70 % by weight) and from 80 to 20 % by weight (preferably from 70 to 30 ~ by weight~, respectively. When the polycarbonate resin is contained in a higher amount than 80 ~ by weight, the melt viscosity of the resulting composition on the molding becomes too high so that the molding property is deteriorated. Further, the weld strength is not improved.
When the polycarbonate resin is contained in A smaller amount than 20 % by weight, the heat resistance is lowered.
When the copolymer is employed, its amoun~ may be normally not more than 90 ~ by weight on the basis or the combined amount of the graft polymer and the copolymer.
When the amount exceeds 90 % by weight, satisfactory impact ~ ~2~3~
~ S ~
resistance is not obtainable.
In this invention, a polyolefin or a certain plasticizer is incorporated into a blend comprising the polycarbonate resin and the graft polymer with or without the copolymer.
As the polyolefin, there may be used polyethylene, polypropylene, ethylene-propylene copolymer, etc. Their mixture may be also usedO In order to assure excellent weld strength and high impact strength, the use of poly-ethylene having a molecular weight of not less than 2,000 or polypropylene having a molecular weight of not less than 5,000 is favorable. The amount of the polyolefin in the composition may be usually from 0.2 to 10 parts by weight to 100 parts by weight of the blend. When the amount is less than 0.2 part by weight, any improvement of the weld strength and the solvent resistance is not produced. When more than 10 parts by weight, the impact strength is markedly lowered, and the weld strength is not improved.
The plasticizer usable in the invention is the one having a light transmission of not less thàn 70 % when determin~d on the film of 20 microns in thickness prepared by a solution of the plasticizer (0.25 g) and acryronitile-styrene copolymer (weight ratio of acryronitrile and styrene being 30 : 70; 0.75 g) in acetone (10 ml) while drying under the atmospheric condition. When -the plasticizer having a light transmission or more than 70 % is used, the purpose of the invention can not be attained. Further, the bleeding of the plasticizer is apt to be produced at the surface of the .

6 - ~

molded product with the resulting composition. Suitable plasticizers may be chosen from ester compounds prepared from dicarboxylic acids (eOg. phthalic acid, adipic acid, sebacic acid, azelaic acid, maleic acid, ~umaric acid, trimellitic acid, citric acid, i-taconic acid, lisinoleic acid) and mono or divalent alcohols (e.g. methanol, ethanol, ethylene glycol, propylene glycol) r epoxy compounds having epoxy groups in the molecule, phosphate compounds (e.g.
diphenyl octyl phosphate, trioctyl phosphate), etc. In case of ester compounds, polymeric ones having a plurality of ester units are favorable to monomeric ones having a single ester unit in volatility. These plasticizers may be employed alone or in combination. The amount of the plasticizer in the composition may be usually from 0.5 to 20 parts by weight to lO0 parts by weight of the blend. When the amount is less than ~.^5 part by weight, any improvement of the weld s~rength is not produced. 1~7hen the amount i5 more than 20 parts by weight, the heat resistance is remark-ably deteriorated.
The graft polymer and the copolymer as above stated may be respectively produced by conventional proce-dures such as emulsion polymerization, suspension poly-merization, bulk polymerization, emulsion-suspension poly-merization or bulk suspension polymerization.
Preparation o~ the thermoplastic composition may be achieved by mixing the said essential a~d optional compo-nents by the aid o~ a conventional mixing apparatus such as a roll or Bumbury's mixer. ~hen desired, any additive such ~59~

as a pigment, a dispersant, a lubricant, a filler, a .
stabilizer, an antistatic agent and a modifier may be incorporated therein.
Practical and presently preferred embodiments of the invention are illustratively shown in the following Examples wherein part~s) and ~ are by weight, unless other-wise indicated.
Examples 1 to 8 and Comparative Examples 1 to 7 1) Polycarbonate resin~-Bisphenol ~ (470 g) and p-t-butylphenol (9.8 g) were suspended in water (1700 ml), and the suspension was stirred while introducing nitrogen therein for 15 minutes to eliminate oxygen therefrom. Then, 45 ~ sodium hydroxide solution (360 g) and me~hylene chloride ~1000 g) were added thereto. The resulting mixture was cooled to ?5C, and phosgene (240 g) was added thereto in 120 minutes. After 15 to 30 minutes, 45 % sodium hydroxide solution t75 g) and triethylamine (1~ g) were added thereto, and the resulting mixture was stirred for 15 minutes to obtain a polymer solution of high viscosity. The aqueous layer was separated, and the organic layer was washed with water to remove salts and alkalis to obtain a polycarbonate resin.
2) Gra~t polymer:-As the graft polymer, commercially availableacrylonitrile-butadiene-styrene copolymer ("~ralastic MV"
manufactured by Sumitomo Naugatuck) was used.

3) Polyolefin:-The following commercially available polyolefins .

were used: .
Polyolefin Molecular weight Polyethylene ("Mitsui Highwax llOP" ~ 1000 manufactured by Mitsui Petrochemical) Polyethylene ("Mitsui Highwax 410P" ~ 4000 manufactured by Mitsui Petrochemical) Polyethylene ("Sumikathene G-801" ~~30000 manufactured by Sumitomo Chemical) Polypropylene ("Biscol 550P" ~ 4000 manufactured by Sanyo Chemical Industry) Polypropylene ("Bistac L" ~50~0 - 10000 manuactured by Chiba Fine~Chemical"

4) Thermoplastic composition:~
The polycarbonate resin, the graft polymer and the polyolefin as stated above were mixed`together in a propor-~ion as shown in Table 1 by the aid of Bumbury's mixer at ~30C for 4 minutes to give a thermoplastic composition.
The physical properties of the obtained thermo-plastic composi~ion are shown in Table 1. The solvent resistance and the weld strength were determined in the following manners:
~ a) Solvent resistance:-Onto the surface of a press molded plate of thethermoplastic composition, a mixture of toluene and cyclo-hexane (weight ratio, 3 : 7) was applied, and the critical strain was calculated according to the following equation:

Critical strain = 3h.X3c.~ x 100 (%) 2~
wherein h is the thickness of the test piece (3 mm~, Xc is the distance between the maximum deflec~ion point and crack ~s~
^\ - 9 -produced point, ~ is the distance between the fixed ~dge and the maximum deflection point and Q is the maximum deflection amount. These values were determined by a measuring apparatus as shown in Fig. 1 of the accompanying drawing. This Figure shows illustratively the section view of the measuring apparatus, and A and A' are press bars, B is the test piece and other symbols have the same meanings as above.
(b) Weld strength:- `
The thermoplastic composition was molded at 260C
through two gates (each 2.5 x 2.0 mm), the distance between them being ioo mm, to make a test piece having 3 mm in thickness and 150 mm in length and in width. The test piece was placed on a cylindrical support of 80 mm in height, 120 mm in inner diameter and 126 mm in outer diameter in a low ~temperature room adjusted to -30Ct and a steel ball of 1 kg was fallen down at the center of the test piece. The maximum energy value (kg.cm) producing no breaka~e was determined.

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g ll -Examples 9 to 18 and Comparative Examp].es ~ to 19 1) Polycarbonate xesin:-As the polycarbonate resin, commercially availablepolycarbonate resin ("Panli~e L-1250W'~manufactured by Teijin Kasei) was used.
2) Graft polymer:-Polybutadiene (50 parts ~as solid components~),potassium persulfate (0.5 part), potassium oleate (0.5 part) and dodecylmercaptan (0.3 part) were mixed together, styrene (36 parts) and acrylonitrile (14 parts) were added thereto, and the resulting mixture was subjected to polymerization at 70C for 3 hours, followed by aging for 1 hour. The reaction mixture was salted out, and the precipitate was collected and dried to obtain a graft polymer.
3) Copolymer:-(A) To a mixture of styrene and acrylonitrile ina weight proportion of 70 : 30 (100 parts), t-dodecylmer-captan (0.1 part) was added, and the resultant mixture was subjected to prepolymerization in a bulk state at 90C for 3 hours. Thereafter, wa~er (210 parts), methyl cellulose ~1.0 part~ and benzoyl peroxide ~0.3 part) were added thereto.
The resul~ing aqueous dispersion was heated from 30C to 90C, and polymerization was carried out for 10 hours. By dehydration rom the reaction mixture, there was obtained a copolymer (A) (intrinsic viscosity, 0.50).
(B) Rs the copolymer(~), commercially available styrene-acrylonitrile copolymer ("5evian NJD'~manufaCtured by Daicel; intrinsic viscosity, 0.63) was used.

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4) Plasticizer:-. The following plasticizers ~ere used:
Plasticizer Liqht transmission (%) .
Diisodecyl phthala-te 88.5 Di-2-~thylhexyl adipate 80.7 Dibutyl sebacate 85.5 Citric acid triester 86.0 Trimellitic acid ester 88.0 Epoxybutyl stearate 52~5 Methylphthalyl glcolate 81.0 Methylacetyl ricinoleate ~2.0 Polyester ~"PN-250'~manufactured 86.S
by Adeka Argus) Tricresyl phosphite 85.0 Epoxy soybean oil ("0-130P"~ 72.0 manufactured by Adeka Argus) Epoxy compound ("Drapex 3.2"~ 53.0 manufactured by Adeka Argus) S) Thermoplastic composition:
~ rhe polycarbonate resin, the gra~t polymer and the copolymer were mixed together with the plasticizer in a proportion as shown in Table 2 by the aid of Bumbury's mixer to give a thermoplastic composition.
The physical properties of the obtained thermo-plastic composition are shown in Table 2~

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Claims

Claims:

1. A thermoplastic composition which comprises a blend comprising 20 to 80 % by weight of a polycarbonate resin and 80 to 20 % by weight of graft polymer obtained by grafting at least one aromatic vinyl compound and at least one of vinyl cyanides and alkyl unsaturated carboxylates onto a conjugated diene rubber or a mixture of said conjugated diene rubber with a copolymer of at least one aromatic vinyl compound and at least one of vinyl cyanides and alkyl unsatu-rated carboxylates, the copolymer being present in an amount of not more than 90 % by weight on the basis of the combined amount of the graft polymer and the copolymer, and a polyolefin or a plasticizer having a light transmission of not less than 70 % when determined on a film of 20 microns in thickness prepared from a solution of the plasticizer (0.25 g) and acrylonitrile-styrene copolymer (weight ratio of acrylonitrile and styrene, 30 : 70; 0.75 g) in acetone (10 ml), the weight proportion of the blend and the polyolefin or the platicizer being 100 : 0.2 - 207

2. The composition according to claim 1, wherein the blend comprises the polycarbonate and the graft polymer.

3. The composition according to claim 2, wherein the polyolefin is contained in an amount of 0.2 to 10 parts by weight based on 100 parts of the blend.

4. The composition according to claim 3, wherein the polyolefin comprises polyethylene having a molecular weight of not less than 2,000 or polypropylene having a molecular weight of not less than 5,000, or their mixture.

5. The composition according to claim 1, wherein the blend comprises the polycarbonate resin, the graft polymer and the copolymer.

6. The composition according to claim 5, wherein the plasticizer is contained in an amount of 0.5 to 20 parts by weight based on 100 parts of the blend.

7. The composition according to claim 6, wherein the plasticizer comprises an ester compound, an epoxy compound or a phosphate compound.